New Haven Sister Cities (NHSC) promotes an awareness of the cultures, customs, and historical heritages of its sister cities by cultivating citizen diplomacy. New Haven has established sister-city relationships with the cities of Afula-Gilboa, Israel; Amalfi, Italy; Avignon, France; Freetown, Sierra Leone; Hué, Vietnam; León, Nicaragua; and Tetlanohcan, Mexico.

NHSC consists of an all-volunteer Board of Directors. The Mayor of New Haven is the Honorary Chairman of the Board of Directors and many of the directors represent major business, educational, social, and cultural interests in the community. Fund-raising events and donations support operations and programs.

NHSC is a member of Sister Cities International and is part of a global network of more than 2,300 partnerships in 150 countries. Sister Cities International promotes peace through mutual respect, understanding and cooperation.